Macefield Vaughan G
School of Medicine, University of Western Sydney Penrith, NSW, Australia.
Front Neurosci. 2011 Dec 6;5:132. doi: 10.3389/fnins.2011.00132. eCollection 2011.
Postganglionic sympathetic axons in awake healthy human subjects, regardless of their identity as muscle vasoconstrictor, cutaneous vasoconstrictor, or sudomotor neurons, discharge with a low firing probability (∼30%), generate low firing rates (∼0.5 Hz) and typically fire only once per cardiac interval. The purpose of the present study was to use modeling of spike trains in an attempt to define the number of preganglionic neurons that drive an individual postganglionic neuron. Artificial spike trains were generated in 1-3 preganglionic neurons converging onto a single postganglionic neuron. Each preganglionic input fired with a mean interval distribution of either 1000, 1500, 2000, 2500, or 3000 ms and the SD varied between 0.5×, 1.0×, and 2.0× the mean interval; the discharge frequency of each preganglionic neuron exhibited positive skewness and kurtosis. Of the 45 patterns examined, the mean discharge properties of the postganglionic neuron could only be explained by it being driven by, on average, two preganglionic neurons firing with a mean interspike interval of 2500 ms and SD of 5000 ms. The mean firing rate resulting from this pattern was 0.22 Hz, comparable to that of spontaneously active muscle vasoconstrictor neurons in healthy subjects (0.40 Hz). Likewise, the distribution of the number of spikes per cardiac interval was similar between the modeled and actual data: 0 spikes (69.5 vs 66.6%), 1 spike (25.6 vs 21.2%), 2 spikes (4.3 vs 6.4%), 3 spikes (0.5 vs 1.7%), and 4 spikes (0.1 vs 0.7%). Although some features of the firing patterns could be explained by the postganglionic neuron being driven by a single preganglionic neuron, none of the emulated firing patterns generated by the firing of three preganglionic neurons matched the discharge of the real neurons. These modeling data indicate that, on average, human postganglionic sympathetic neurons are driven by two preganglionic inputs.
在清醒的健康人类受试者中，节后交感神经轴突，无论其身份是肌肉血管收缩神经元、皮肤血管收缩神经元还是发汗运动神经元，放电概率都很低（约30%），放电频率也很低（约0.5赫兹），并且通常每个心动周期仅放电一次。本研究的目的是通过对脉冲序列进行建模，试图确定驱动单个节后神经元的节前神经元数量。在汇聚到单个节后神经元的1 - 3个节前神经元中生成人工脉冲序列。每个节前输入的平均间隔分布为1000、1500、2000、2500或3000毫秒，标准差在平均间隔的0.5倍、1.0倍和2.0倍之间变化；每个节前神经元的放电频率呈现正偏态和峰态。在所研究的45种模式中，节后神经元的平均放电特性只能通过平均由两个节前神经元驱动来解释，这两个节前神经元的平均峰峰间隔为2500毫秒，标准差为5000毫秒。这种模式产生的平均放电频率为0.22赫兹，与健康受试者中自发活动的肌肉血管收缩神经元的频率（0.40赫兹）相当。同样，每个心动周期的脉冲数量分布在建模数据和实际数据之间也相似：0个脉冲（69.5%对66.6%）、1个脉冲（25.6%对21.2%）、2个脉冲（4.3%对6.4%）、3个脉冲（0.5%对1.7%）和4个脉冲（0.1%对0.7%）。尽管放电模式的一些特征可以通过节后神经元由单个节前神经元驱动来解释，但由三个节前神经元放电产生的模拟放电模式均与真实神经元的放电不匹配。这些建模数据表明，平均而言，人类节后交感神经元由两个节前输入驱动。
